When you turn the key to the on position, do you hear the fuel pump come on for a few seconds? You can turn it on over and over again to listen. It will only stay on for a very short time if the fuel pump is working. Does it have spark when cranking?

Sounds like what the Windstar did to me. Worked on everything that I could think of and it turned out to be a really rusty fusable link under the hood in the distribution box. Replaced that and have had no issues starting again.